Pure propylene oxide is in demand for the preparation of urethane foams, for example. One of the most widespread procedures for producing propylene oxide has been the epoxidation of propylene. Typical processes are described in U.S. Pat. Nos. 3,350,422 and 3,523,956. When tertiary butyl hydroperoxide is used as the oxidizing agent, the desired propylene oxide is formed. Relatively minor quantities of acetaldehyde, propionaldehyde, acrylic aldehyde, acetone, methanol, hexenes, water, are formed, as well as tertiary butyl alcohol. Fractionation of the reaction product is required.
One of the more efficient agents for oxidizing propylene to propylene oxide is tertiary butyl hydroperoxide, because its reduction product, tertiary butyl alcohol, may be isolated and sold or recycled to reform tertiary butyl hydroperoxide by the following steps: ##STR1##
In the recovery of tertiary butyl alcohol for dehydration to isobutylene, the tertiary butyl alcohol is vaporized and this step has proven to be particularly troublesome. The crude tertiary butyl alcohol discharged as a product from the distillation of the epoxidation products contains impurities which polymerize. The polymers are deposited on heat exchange surfaces of the equipment employed to vaporize the tertiary butyl alcohol.
It is an object of the present invention to reduce the fouling of the heat transfer surface in the tertiary butyl alcohol vaporizer thereby increasing the on-stream time between cleanings.
Further, it is an object of the present invention to reduce the organic content of the waste water discharge from the propylene oxide manufacturing plant.
Another object is to soften the deposits on the heat exchanger surfaces in the tertiary butyl alcohol vaporizer so that such deposits are more easily removed.